Novel fuel production plant and seawater desalination system for use therein

ABSTRACT

A novel fuel producing section produces synthesized gas from a feedstock and synthesizes novel fuel from the synthesized gas thus produced, and has exhaust heat recovery boilers for generating steam by recovering excess heat generated from the synthesizing processes. An exhaust heat utilizing section includes steam turbines driven with the steam generated from the exhaust heat recovery boilers. An open circulation cooling water supply section supplies cooling water for a plant, including water for cooling exhausts of the steam turbines, and includes a seawater desalination system for desalinating seawater by the evaporation method and supplying desalinated water to replenish the cooling water. The cooling water supplied from the open circulation cooling water supply section is used in condensing of the desalinated water produced by the seawater desalination system.

TECHNICAL FIELD

The present invention relates to a novel fuel production plant forproducing novel fuel, and to a seawater desalination system for use inthe plant.

BACKGROUND ART

Recently, attention has been focused on plants for producing novel fuel,such as Gas-To-Liquid (GTL) and dimethylether (DME). As a novel fuelproduction plant, one known example for producing dimethylether by usingnatural gas as a feedstock is disclosed in, e.g., JP,A 10-195008.

DISCLOSURE OF THE INVENTION

In plants for producing novel fuel, such as GTL and DME, (hereinafterreferred to as “novel fuel production plants” or simply as “plants”),for example, a partial oxidation method or an auto-thermal reformingmethod using hydrocarbons, etc. as a feedstock is employed to producesynthesized gas necessary for synthesizing fuel. In those synthesizedgas producing methods, the temperature of the synthesized gas at anoutlet of a reaction/reforming furnace is very high (1200-1500° C.). Onthe other hand, from the viewpoint of synthesizing fuel in a succeedingstage, the synthesized gas has to be cooled down to synthesizingreaction temperatures (200-300° C.) at an inlet of a fuel synthesizingreactor. Also, the fuel synthesizing reaction is itself an exothermicreaction. In the novel fuel production plant, therefore, a large amountof excess heat is inevitable generated, thus resulting in the necessityof installing exhaust heat boilers to generate high- and medium-pressuresteam for heat recovery. The generated high- and medium-pressure steamcan be utilized by steam turbines for driving compressors, pumps,generators, etc. in the plant.

A system using steam turbines requires a large amount of cooling waterto condense steam. Hitherto, in facilities requiring a large amount ofcooling water, seawater has been used in many cases primarily for theeconomical reason. However, the merit resulting from using seawater asthe cooling water is reduced because of regulations, such as chargingfor use of seawater and a limitation on the temperature differencebetween seawater and cooling water (i.e., the difference between thetemperature of returned seawater and the temperature of suppliedseawater), which have been legislated with recent increasingenvironmental awareness. The limitation on the temperature differencebetween seawater and cooling water often increases the amount ofrequired cooling water 3-5 times that required in the past. Under such asituation, large-scaled water taking-in equipment has to be installedand the economical merit is lost in most cases. For that reason, it istried to employ, as a cooling water system for a plant, an opencirculation cooling water system provided with a cooling tower, and tominimize the amount of used seawater by compensating for only losses,which are caused due to evaporation, scattering and forced blow from thecooling tower, with desalination of seawater.

In such a try, for the desalination of seawater, a reverse osmosismembrane method is primarily studied because this method requires a lessseawater intake amount in spite of accompanying the problems that theremaining salinity is high, a plant cannot be practically installed insome cases depending on properties of seawater, and a membrane occupyingabout ⅓ of the overall plant cost has to be frequently replaced, thusresulting in a higher maintenance cost. An evaporation method, e.g., amultistage flash method or a multiple effect method, which is apotential candidate utilizing excess low-pressure steam, is not takeninto consideration because it requires a seawater intake amount 3-4times that required in a system using the reverse osmosis membranemethod for the same amount of produced water even when theintake-discharge temperature difference of seawater is 10° C. that hasbeen allowed in the past, and it requires a larger seawater intakeamount when the intake-discharge temperature difference of seawater islimited to be lower than 10° C.

An object of the present invention is to provide a novel fuel productionplant and a seawater desalination system for use therein in which anevaporation water production system can be applied at a seawater intakeamount comparable to that required in a system using the reverse osmosismembrane method, the degree of freedom in selecting the plantinstallation site is high, salinity of produced water is reduced ascompared with that in the case using the reverse osmosis membranemethod, and the merit of the evaporation water production system havinga low maintenance cost can be enjoyed.

To achieve the above object, the present invention provides a novel fuelproduction plant for producing synthesized gas from a feedstock andproducing novel fuel from the produced synthesized gas, the novel fuelproduction plant comprising an exhaust heat recovery boiler forgenerating steam by recovering excess heat generated from the fuelproduction processes, the novel fuel production plant further comprisingan exhaust heat utilizing section including a steam turbine driven withthe steam generated from the exhaust heat recovery boiler, an opencirculation cooling water supply section for supplying cooling water fora plant, including water for cooling exhaust of the steam turbine, and aseawater desalination system using an evaporation method and supplyingdesalinated water to replenish the open circulation cooling water,wherein the cooling water supplied from the open circulation coolingwater supply section is used in condensing of the desalinated waterproduced by the seawater desalination system.

With that arrangement, fresh water can be produced at a seawater intakeamount comparable to that required in a system using the reverse osmosismembrane method, and the cooling water can be supplied with a lowerremaining salinity in the produced water and a lower maintenance costthan those in the case using the reverse osmosis membrane method.

Also, to achieve the above object, the present invention provides aseawater desalination system for desalinating seawater by using anevaporation method and supplying desalinated water, wherein coolingwater supplied from an open circulation cooling water supply section isused in condensing of the desalinated water produced by the seawaterdesalination system.

With that arrangement, fresh water can be produced at a seawater intakeamount comparable to that required in a system using the reverse osmosismembrane method, and the cooling water can be supplied with a lowerremaining salinity in the produced water and a lower maintenance costthan those in the system using the reverse osmosis membrane method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the construction of a novel fuel productionplant according to one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The construction of a novel fuel production plant according to oneembodiment of the present invention will be described below withreference to FIG. 1.

FIG. 1 is a diagram showing the construction of the novel fuelproduction plant according to one embodiment of the present invention.

The novel fuel production plant of this embodiment comprises a novelfuel producing section 100, an exhaust heat utilizing section 200, and acooling water supply section 300. The novel fuel producing section 100produces new fuel from a feedstock and generates steam by utilizingexhaust heat. In the exhaust heat utilizing section 200, steam turbinesare driven using the steam generated by the novel fuel producing section100, to thereby drive rotary machines, etc. The cooling water supplysection 300 supplies cooling water used in condensers for the steamturbines in the exhaust heat utilizing section 200.

The novel fuel producing section 100 comprises an air compressor 1, anair separator 2, an oxygen booster 3, a reaction/reforming furnace 4,exhaust heat recovery boilers 5 and 8, a fuel synthesizing reactor 7,etc.

The feedstock is supplied to the reaction/reforming furnace 4 through apiping 50. Usable raw materials supplied as the feedstock includes, forexample, hydrocarbons such as coal, oil and natural gas, biomass, wastedplastics, etc. In this embodiment, natural gas is used as the feedstock.Though not shown, steam, carbon dioxide, etc. may also be supplied inaddition to those raw materials. Further, the reaction/reforming furnace4 is supplied with oxygen through a piping 51. The oxygen is obtained bycompressing air by the air compressor 1, separating the compressed airby the air separator 2, and boosting the pressure of the separatedoxygen by the oxygen booster 3. In the reaction/reforming furnace 4,synthesized gas mainly consisted of hydrogen and carbon monoxide isproduced from the feedstock gas supplied through the piping 50 and theoxygen supplied through the piping 51 by partial oxidation orauto-thermal reforming, for example. The produced synthesized gas istaken out through a piping 52.

The hot synthesized gas thus produced by the reaction/reforming furnace4 is supplied to the exhaust heat recovery boiler 5 where steam(high-pressure steam) is generated to lower the temperature of thesynthesized gas. The synthesized gas is then supplied to the fuelsynthesizing reactor 7. In the fuel synthesizing reactor 7, thesynthesized gas is further synthesized into novel fuel under the actionof a catalyst. The reaction heat generated at this time is recovered bygenerating steam (medium-pressure steam) in the exhaust heat recoveryboiler 8. The novel fuel synthesized by the fuel synthesizing reactor 7,unreacted gases, etc. are sent via a piping 53 to a succeedingliquefying/refining step for liquefaction and refining. The heat of thefuel synthesizing reaction can be recovered from reaction products afterexiting the reactor as shown, or can be recovered directly from theinterior of the reactor in other cases.

With the above-mentioned synthesized gas production method, thesynthesized gas at an outlet of the reaction/reforming furnace 4 hasvery high temperatures. On the other hand, the fuel synthesizingreaction carried out in the fuel synthesizing reactor 7 of thesucceeding stage is an exothermic reaction, and the synthesized gas atan inlet of the fuel synthesizing reactor 7 requires to be cooled downto a temperature suitable for the synthesizing reaction. In the novelfuel production plant, since a large amount of excess heat is generatedwith that necessity of cooling the synthesized gas, the exhaust heatrecovery boilers 5, 8 are installed to generate high- andmedium-pressure steam for heat recovery.

The generated high- and medium-pressure steam is used in the exhaustheat utilizing section 200 by the steam turbines for drivingcompressors, pumps, generators, etc. in the plant. However, low-pressuresteam is rather excessive because it is used just as a heat source for areboiler in a part of equipment for liquefying and refining the fuelsynthesizing reaction gas, a heat source for degassing feedwater for aboiler, etc. Also, if many steam condensing turbines are used from theviewpoint of operating the steam turbines with higher efficiency andkeeping steam balance in consideration of the less number of heatsources requiring the low-pressure steam, a larger amount of coolingwater is required to condense steam correspondingly.

The exhaust heat utilizing section 200 will be described below. Theexhaust heat utilizing section 200 comprises a high-pressure steam line,a medium-pressure steam line, and a low-pressure steam line.

The high-pressure steam line is constituted by the exhaust heat recoveryboiler 5, a high-pressure boiler 6, and a high-pressure steam header 54.High-pressure steam generated by the exhaust heat recovery boiler 5 isused by a steam turbine 9 for driving the feedstock air compressor 1, asteam turbine 12 for driving the oxygen booster 3, etc. Exhausts of thedriving steam turbines 9, 12 are cooled in condensers 10, 13, etc. byplant circulation cooling water, and are returned to a degasser 25 bycondensate transfer pumps 11, 14, etc. High-pressure boiler feedwater iswithdrawn from the degasser 25 and is boosted up to a predeterminedpressure by a high-pressure boiler feedwater pump 27, followed by beingsupplied to the exhaust heat recovery boiler 5 and the high-pressureboiler 6. Also, medium-pressure boiler feedwater is withdrawn from thedegasser 25 and is boosted up to a predetermined pressure by amedium-pressure boiler feedwater pump 26, followed by being supplied tothe exhaust heat recovery boiler 8. Additionally, the high-pressuresteam that is insufficient from the viewpoint of steam balance issupplied to the high-pressure steam header 54 by the high-pressureboiler 6.

The medium-pressure steam line is constituted by the exhaust heatrecovery boiler 8 and a medium-pressure steam header 55. Medium-pressuresteam generated by the exhaust heat recovery boiler 8 is used by apump-driving steam turbine 17, steam turbines 18, 21 for driving processgas compressors, etc. From the viewpoint of steam balance, thepump-driving steam turbine 17, the steam turbine 18 for driving theprocess gas compressor, etc. operate as backpressure turbines and supplythe low-pressure steam to a low-pressure steam header 56. The steamturbine 21 for driving the process gas compressor operates as acondensing turbine. From the viewpoint of steam balance, exhausts of thesteam turbine 21 for driving the process gas compressor, etc. are cooledin a condenser 22, etc. by the plant circulation cooling water, and arereturned to the degasser 25 by a condensate transfer pump 23, etc.

Here, a condensing turbine may be used as the steam turbine 18. Takinginto account the amount of the low-pressure steam used by a brine heater40, however, of a condensing turbine is used as the steam turbine 18 fordriving the process gas compressor, the amount of the suppliedlow-pressure steam becomes insufficient. For that reason, in thisembodiment, a backpressure turbine is used to increase the amount of thesupplied low-pressure steam.

The medium-pressure steam line further includes a gas turbine generator36 and a gas-turbine exhaust heat boiler 37. The gas-turbine exhaustheat boiler 37 generates medium-pressure steam and supplies thegenerated medium-pressure steam to a medium-pressure steam header 55.

The lower-pressure steam line is constituted by a lower-pressure steamheader 56 and supplies the lower-pressure steam, which has been receivedfrom the pump-driving steam turbine 17, etc., to a reboiler 47, thedegasser 25, etc. The lower-pressure steam is also supplied to the brineheater 40 and utilized as a heat source for a seawater desalinationsystem using the evaporation method. In this case, excess steam is setto zero by adjusting a water production rate in the seawaterdesalination system using the evaporation method.

The cooling water supply section 300 will be described below. Thecooling water supply section 300 comprises a plant open circulationcooling-water line and a water production line.

The plant open circulation cooling-water line is constituted by acooling tower 34, a cooling water circulation pump 35, and a coolingwater circulation piping 59. The cooling water is supplied to thecondensers 10, 13, 22, etc. through the cooling water circulation piping59. The cooling water having temperature raised with heat exchanges inthe condensers 10, 13, 22, etc. is cooled in the cooling tower 34 usingthe atmosphere, and is circulated within the line after pressure isboosted by the cooling water circulation pump 35. A part of the coolingwater lost by evaporation during the cooling step in the cooling tower34 using the atmosphere is replenished from the water production line.

The water production line employs the multistage flash method as oneexample of the evaporation method. The water production line isconstituted by a heat radiating section 38 of a multistage-flash waterproduction system, a heat recovering section 39 of the multistage-flashwater production system, the brine heater 40, a seawater/brine heatexchanger 41, a degassing tank 42, a brine circulation pump 43, and avacuum generator 44.

The heat radiating section 38 of the multistage-flash water productionsystem cools and condenses steam evaporated from circulating brine torecover fresh water. Desalted water thus produced is temporarily storedin a desalted water tank 31 and then supplied as makeup water for theplant circulation cooling-water line by a desalted water supply pump 32.The plant circulation cooling water supplied through a piping 66 is usedas a fresh water condensing coolant in the heat radiating section 38 ofthe multistage-flash water production system. The cooling water exitingthe heat radiating section 38 of the multistage-flash water productionsystem is returned to the cooling tower 34 through a piping 63.

The seawater/brine heat exchanger 41 performs heat exchange betweenseawater supplied through a piping 60 and drain brine discharged througha piping 61 so that the temperature of the discharged brine is loweredand heat is recovered to the supplied seawater. The seawater havingpassed the seawater/brine heat exchanger 41 is degassed in a degassingtank 42 and then supplied, through a piping 65, to low-temperaturecirculating brine that is circulated through a low-temperaturecirculating brine 64.

The low-temperature circulating brine 64 to which seawater has beennewly replenished is boosted in pressure by the brine circulation pump43, and is then introduced to the heat recovering section 39 of themultistage-flash water production system. Here, the low-temperaturecirculating brine 64 serves to not only cool and condense the steamevaporated from high-temperature circulating brine, but also to recoverheat for raising the temperature thereof.

The brine having temperature further raised by the brine heater 40 usingthe low-pressure steam becomes high-temperature circulating brine 67that is successively introduced for flashing to respective steps(stages) of both the heat recovering section 39 and the heat radiatingsection 38 of the multistage-flash water production system, which havebeen held in lower-pressure states by the vacuum generator 44 using themedium-pressure steam. The high-temperature circulating brine 67 isgradually condensed and cooled while being flashed in the respectivestages. Then, a part of the high-temperature circulating brine is blownoff externally of the line from the heat radiating section 38 of themultistage-flash water production system through the piping 61, and theremaining high-temperature circulating brine is recirculated as thelow-temperature circulating brine 64.

Note that the evaporation method used in the water production line isnot limited to the above-described multistage flash method, and themultiple effect method may be used instead. Further, both the multistageflash method and the multiple effect method may be used in a combinedmanner.

A first feature of the above-described novel fuel production plant ofthis embodiment resides in that the plant circulation cooling watersupplied through the piping 66 is used as the fresh water condensingcoolant in the heat radiating section 38 of the multistage-flash waterproduction system. For example, when fresh water is produced at a rateof 750 t/hour in the water production line, the known seawaterdesalination system using the reverse osmosis membrane method has totake in seawater at a rate of 1500 t/hour, i.e., about twice the rate ofthe required fresh water, on condition that the known system is onehaving the highest fresh water recovery rate. On the other hand, if itis assumed that the evaporation method requires a seawater intake amountfour times that required by the reverse osmosis membrane method when thetemperature difference between the seawater and the cooling water is 10°C., the seawater intake amount required in the known seawaterdesalination system using the evaporation method is 6000 t/hour. Of 6000t/hour, 4500 t/hour is the amount of seawater used as the fresh watercondensing coolant in the heat radiating section 38 of themultistage-flash water production system, and 1500 t/hour is the amountof seawater required for the water production. In this case, by usingthe plant circulation cooling water supplied through the piping 66 asthe fresh water condensing coolant in the heat radiating section 38 ofthe multistage-flash water production system, an amount Q1 of seawaterto be taken in through the piping 60 is given as 1500 t/hour that isequal to the amount required in the known seawater desalination systemusing the reverse osmosis membrane method. If the temperature differencebetween the seawater and the cooling water is limited to 2° C., i.e., toa most tightly controlled level in recent years, the known seawaterdesalination system using the evaporation method requires a very largeseawater intake amount of 24000 t/hour (=4500×10/2+1500). However, whenthe plant circulation cooling water supplied through the piping 66 isused as the fresh water condensing coolant in the heat radiating section38 of the multistage-flash water production system, the seawater intakeamount is not affected by the limitation on the temperature differencebetween the seawater and the cooling water and remains at 1500 t/hour.Though depending on the cooling capability of the cooling tower 34, itis general that a temperature difference ΔT2 between the cooling waterflowing through the piping 66 and the cooling water returned from thepiping 63 is set to 10° C. In this case, because the cooling efficiencyis increased 5 times as the temperature difference increases 5 times, anamount Q2 of the cooling water supplied to the heat radiating section 38of the multistage-flash water production system through the piping 66 isgiven as 4500 t/hour {=(24000−1500) t/hour×⅕}. Since an amount Q3 of thecooling water supplied to the exhaust heat utilizing section 200 fromthe cooling tower 34 through the piping 59 is, e.g., about 33600 t/hour,the amount Q2 of the cooling water supplied from the piping 66 to theheat radiating section 38 of the multistage-flash water productionsystem through the piping 66 is about 13% of the above-mentioned coolingwater amount Q3.

Thus, according to this embodiment, by using the plant circulationcooling water supplied through the piping 66 as the fresh watercondensing coolant in the heat radiating section 38 of themultistage-flash water production system, the seawater intake amount canbe reduced to a level comparable to that required in the known seawaterdesalination system using the reverse osmosis membrane method. Also,according to this embodiment, there is no need of considering corrosionresistance to salt contained in the seawater with respect to pipingmaterials for the heat radiating section 38 of the multistage-flashwater production system, and hence a relatively inexpensive material canalso be used.

A second feature of the present invention resides in that theevaporation method, e.g., the multistage flash method or the multipleeffect method, is applied to the water production line for desalinatingseawater. With the second feature, replacement of an expensive membraneis no longer required and the maintenance cost of the water productionsystem is reduced. Further, comparing the reverse osmosis membranemethod and the evaporation method, it is general that the evaporationmethod can produce fresh water with a lower remaining salinity than thereverse osmosis membrane method. As a result, the maintenance cost ofthe cooling water line is also reduced.

A third feature of this embodiment resides in that a backpressureturbine is used as the steam turbine 18 for driving the process gascompressor to compensate for the amount of the low-pressure steamconsumed by the brine heater 40. With the third feature, the amount ofthe supplied lower-pressure steam can be increased. Also, since the useof a backpressure turbine eliminates the need of an additional condenserfor use with a condensing turbine, the amount of the circulated coolingwater is reduced correspondingly. Even though the amount Q2 of thecooling water circulated through the heat radiating section 38 of themultistage-flash water production system is increased by 4500 t/hour asdescribed above, the amount of the circulated cooling water can bereduced by about 1500 t/hour as a result of not using the additionalcondenser.

A fourth feature of this embodiment resides in that the gas turbinegenerator 36 is installed as a power supply source for the plant and thegas-turbine exhaust heat boiler 37 is installed to generate themedium-pressure steam. As the power supply source for the plant, a steamturbine can be installed at a position indicated by a symbol X in thedrawing similarly to the steam turbine 12. In the case using a steamturbine as the power supply source for the plant, however, that steamturbine has to be constituted in similar arrangement of the drivingsteam turbine 21, the condenser 13 and the condensate transfer pump 14,and hence an additional condenser is required. Since the use of the gasturbine eliminates the need of an additional condenser, the amount ofthe circulated cooling water is reduced correspondingly. Even though theamount Q2 of the cooling water circulated through the heat radiatingsection 38 of the multistage-flash water production system is increasedby, e.g., 4500 t/hour as described above, the amount of the circulatedcooling water can be reduced by about 3100 t/hour as a result of notusing the additional condenser.

Consequently, by using a backpressure turbine as the steam turbine 18,using the gas turbine generator 36 in place of the steam turbinegenerator, and installing the gas turbine exhaust heat boiler 37, theamount of the circulated cooling water can be reduced by the amount ofthe cooling water used by the two condensers, i.e., 4600 t/hour (=1500t/hour+3100 t/hour). With this embodiment, as described above, in spiteof the amount Q2 of the cooling water supplied through the piping 66being increased by 4500 t/hour when the plant circulation cooling watersupplied through the piping 66 is used as the fresh water condensingcoolant in the heat radiating section 38 of the multistage-flash waterproduction system, the amount of the circulated cooling water can bereduced by the amount of the cooling water used by the two condensers,i.e., 4600 t/hour, and therefore the amount of the circulated coolingwater can be reduced by 100 t/hour as a whole. Although those numericalvalues are shown merely by way of example, it is concluded that, evenwith the amount of the cooling water increased by using the plantcirculation cooling water supplied through the piping 66 as the freshwater condensing coolant in the heat radiating section 38 of themultistage-flash water production system, the total amount of thecirculated cooling water can be reduced to a level comparable to orsmaller than that in the system using the reverse osmosis membranemethod by modifying the other arrangement.

Further, by using the gas turbine generator as the power supply sourcefor the plant, the novel fuel production plant of this embodiment can bestarted up on a stand-alone basis, thus resulting in higher operabilityof the plant. Also, since the use of the evaporation method in the waterproduction system eliminates the need of a high-pressure seawater pumpconsuming a large quantity of power, which has been required in thereverse osmosis membrane system, the output power of the generator canbe reduced by about 15%. Additionally, since a gas turbine is used as agenerator driver, the amount of the required high-pressure steam can bereduced correspondingly and so can be the capacity in operation of thehigh-pressure boiler.

A fifth feature of this embodiment resides in that the lower-pressuresteam generated in the exhaust heat utilizing section 200 is supplied toand utilized by the brine heater 40 of the multistage-flash waterproduction system. Here, if the lower-pressure steam is excessive, theexcess steam can be consumed by changing a water production rate of thewater production system, or it can be eliminated by optimizing the steambalance. In the case adjusting the water production rate, if thelower-pressure steam is excessive and the water production rate can beadjusted to a lower value, it is also possible to reduce the number ofstages and the number of evaporators in the water production system,thereby cutting the equipment cost.

A sixth feature of this embodiment resides in that the seawater/brineheat exchanger 41 is installed to perform heat exchange between thebrine discharged from the evaporation water production system and theseawater supplied to it. With the sixth feature, heat can be recoveredand the temperature of the discharged brine can be kept not higher thana predetermined value when the intake-discharge temperature differenceof seawater is specified as a result of control for environmentalprotection.

Thus, it is possible to optimize the steam balance of the plant, toeliminate the excess steam in the plant, and to increase the overallthermal efficiency of the plant by changing a part of steam turbinedriven machines to a gas turbine driven machine, changing a part ofcondensing turbines to a backpressure turbine, recovering heat from thedischarged brine, and adjusting the water production rate of theevaporation water production system.

The seawater desalination system according to this embodiment isintended to desalinate seawater by using the evaporation method and tosupply the desalinated water for replenishment of the cooling water, andit is featured in that the cooling water supplied from the opencirculation cooling water supply section is used in condensing of thedesalinated water produced by the seawater desalination system. Theseawater desalination system can be employed not only to supply thecooling water in the novel fuel production plant, but also as a freshwater supply source in an oil refinery, a chemical plant, asteam-turbine power generation plant, etc.

INDUSTRIAL APPLICABILITY

According to the present invention, in a novel fuel production plant anda seawater desalination system for use therein which are installed in adistrict undergoing restriction in use of seawater, a water productionsystem using the evaporation method can be employed with a seawaterintake amount comparable to that required in a system using the reverseosmosis membrane method, and the merit of the evaporation waterproduction system having a lower maintenance cost than the reverseosmosis membrane method can be enjoyed.

1. A novel fuel production plant for producing synthesized gas from afeedstock and producing novel fuel from the produced synthesized gas,said novel fuel production plant comprising an exhaust heat recoveryboiler for generating steam by recovering excess heat generated from thefuel production processes, said novel fuel production plant furthercomprising: an exhaust heat utilizing section including a steam turbinedriven with the steam generated from said exhaust heat recovery boiler,an open circulation cooling water supply section for supplying coolingwater for a plant, including water for cooling exhaust of said steamturbine, and a seawater desalination system using an evaporation methodwith steam utilized as a heat source and supplying desalinated water toreplenish the open circulation cooling water, wherein the cooling watersupplied from said open circulation cooling water supply section is usedin condensing of the desalinated water produced by said seawaterdesalination system.
 2. The novel fuel production plant according toclaim 1, wherein the evaporation method used in said seawaterdesalination system is a multistage flash method, a multiple effectmethod, or a combination of both the methods.
 3. The novel fuelproduction plant according to claim 1, wherein a gas turbine is used todrive a machine to be driven.
 4. The novel fuel production plantaccording to claim 3, further comprising a gas turbine exhaust heatboiler for generating steam with exhaust heat of said gas turbine,wherein the steam generated by said gas turbine exhaust heat boiler issupplied to said exhaust heat utilizing section.
 5. The novel fuelproduction plant according to claim 1, further comprising a heatexchanger for performing heat exchange between brine discharged fromsaid seawater desalination system and seawater as feed material suppliedto said seawater desalination system.
 6. The novel fuel production plantaccording to claim 1, wherein a water production rate of said seawaterdesalination system is modified such that excess steam generated in saidplant is consumed as a heat source for said seawater desalinationsystem.
 7. A seawater desalination system for desalinating seawater byusing an evaporation method with steam utilized as a heat source andsupplying desalinated water, wherein cooling water supplied from an opencirculation cooling water supply section is used in condensing of thedesalinated water produced by said seawater desalination system.